1998Cr-V

Hello All,
I purchased my 98 Cr-V auto 115K about 2 months ago and it has been running great with no complaints as of yet. About a week ago, the CEL illuminated. When I took it into Pep Boys to have it read, the dreaded P0420 showed up. Now, there were no other codes present, just the one above. The mechanic at Pep Boys told me the obvious, my cat is going bad. However, I have not noticed any decrease in MPG or power since the CEL came on. Also, about a day ago while driving, the CEL disappeared! I am quite confused by this. Although happy about the CEL turning off, I am wondering what would cause this and what is ahead of me in regards to fixing the issue (If there is one). Any input would be appreciated!

NMJimCRV

I believe you get 0420 as an indicator that the pre-cat o2 sensor (bank 1) is indicating a bad fuel mixture. 0430 indicates the post-cat o2 sensor (bank 2). You may have an o2 sensor that is going out, or could be having mixture problems. I believe you had a prior post somewhere here stating you also had a timing error code? That may be causing the o2 sensor codes. I would start with the timing issue and see if that corrects the 0420 and 0430 codes.

1998Cr-V

This is my first post. You must have me confused with someone else. I appreciate your reply. I will have to check out the O2 sensors and see if that could be the issue.

Runnerdown

O2 sensors throw seperate codes. 99.9% of the time you have a failed cat which is not a surprise after 15-16 years. The code can come on and off for a while and will eventually stay on all the time. There are several ways to fix this depending on your budget.

NMJimCRV

Ahh, right. You posted a reply up about this in another thread about this same issue - that user had codes for timing and 0420 and 0430. Gotcha.

If you have access to a pull it yard that has a junker CRV you may see if an o2 sensor is left on that bad boy and pull it. Way cheaper than buying a brand new one to test. But, you can pull yours and do some bench testing. I'll see if I can find something in the RM about it and post it up.

NMJimCRV

Runner - if the pre-cat sensor was failing would that be an indicator of the cat? Just wondering, as I have never worked on the o2 sensors, but its job is to test the exhaust before entering the cat, right? If the post-cat sensor is off then I could see it indicating a bad cat. Which is why I am wondering if 0420 ALWAYS is from the pre-cat sensor and 0430 from the post-cat sensor. I tried to find a web page that confirmed that, and the closest I got was from engines-code.com, where they indicate 0420 is from bank 1, 0430 is from bank 2. Of course, it gives the same info for both codes, so not much help there.

I also am thinking that the pre-cat sensor can throw codes if you fuel mix and engine timing are off. It is sending the ECU info to adjust the mixture, but if the timing is off or some other engine issue then it keeps getting out of whack. But I would think he would be getting another code if that were the case.

EDITED:

But I am with you on the likelihood that the cat is gummed up after all this time. OP - I would price this and start saving pennies to get ready to replace the cat at some future point. Go here to get the RM to make your life WAY easier:

http://www.google.com/url?sa=t&rct=j...77412846,d.aWw